This invention relates generally to liquid heaters of the electrode type in which an electrically conductive liquid is heated by an electrical current passing between immersed electrodes and more particularly concerns an electrode type liquid heater in which the heating of the liquid is controlled by immersing the electrodes in the liquid only when additional liquid is flowing into the heater.
Electrode type liquid heaters are capable of rapidly heating small quantities of liquids such as water for use in homes. Their rapid heating ability eliminates the requirement of storing large quantities of heated water for use upon demand such as is required by resistance type electrical water heaters. The small size of an electrode type water heater, due to the absence of the large quantity of stored heated water, makes electrode type water heaters ideally suited for mobile homes or apartments or other applications where space is at a premium.
In an electrode type liquid heater, an electrically conductive liquid is heated by passing an electrical current directly through the liquid between two or more electrodes immersed in the liquid. As is well known, electrical current flows between the electrodes in response to a voltage differential applied across the electrodes.
In the past, various means have been developed to control the flow of current and the liquid heating resulting therefrom. An electrical thermostat in contact with the liquid within the heater may be used as a switch to control the application of the voltage differential to electrodes permanently immersed in the liquid as the temperature of the liquid falls below or rises above preselected temperatures. Alternatively, a voltage differential may be constantly applied across a plurality of electrodes and the flow of electrical current between them controlled by immersing and removing one or more of the electrodes from the liquid. U.S. Pat. No. 3,144,546, of which the present applicant is a co-inventor, discloses an electrode type liquid heater in which a mechanical thermostat immersed within the liquid is linked to a pivoting arm carrying an electrode. As the temperature of the liquid within the heater drops, the thermostat contracts and causes the arm to pivot downwardly, immersing the electrode in the liquid. As the liquid is heated, the thermostat expands and thereby causes the arm to pivot upwardly, lifting the electrode from the liquid. In U.S. Pat. No. 3,809,857, of which the present applicant is inventor, electrodes are mounted on a counterbalanced rotatably buoyant body floating within the liquid heater. A mechanical thermostat, which is mounted to the buoyant body generally opposite the electrodes and immersed in the liquid within the cylinder, extends and retracts an attached movable counterweight. Retraction of the counterweight in response to cooling of the liquid causes the counterweighted side of the body to rotate upwardly, immersing the electrodes on the opposite side of the body. Extension of the counterweight in response to heating of the liquid causes the counterweighted side of the cylinder to rotate downwardly, lifting the electrodes on the opposite side from the liquid. In U.S. Pat. No. 4,326,120, of which the present applicant is inventor, electrodes are mounted to a counterbalanced rotatable buoyant body opposite a fixed counterweight. The electrodes are immersed and withdrawn from the liquid by rotation of the body in response to a bimetallic coiled spring thermostat mounted about the pivot axis of the body and immersed in the liquid within the heater.
Although each of these temperature controlled liquid heaters accomplishes its intended function, all rely upon the mechanical expansion and contraction of non-rigid thermostats or bimetallic springs to provide the immersing force necessary to move the electrodes into the liquid. The liquid heater of the current invention develops that force in a different manner, from the discharge of the liquid flowing into the heater onto a substantially rigid surface of the heating assembly, preferably shaped to form a cup capable of capturing a portion of the flowing liquid.
Accordingly, it is an object of this invention to provide an improved electrode type liquid heater which develops an immersing force from the discharge of liquid flowing into the heater onto a surface connected to movable electrodes in order to control the heating of the liquid by immersing the electrodes.
It is another object of this invention to provide an improved electrode type liquid heater which develops a gravitational immersing force by capturing liquid flowing into the heater in a cup.
It is another object of this invention to provide an improved electrode type liquid heater which develops the immersing force from the impact upon a substantially rigid surface of the liquid flowing into the heater.